Of the 12.8 million people who live in the province, fully 49.2 per cent, or 6.3 million people, draw their drinking water from the massive lake. It’s by far the most drawn upon source of water to sustain Ontario’s growing population.

But on the other end of the spectrum are dozens of communities that don’t have a municipal drinking water system at all. A total of 42 Ontario communities are listed by the province, with a combined population of nearly 140,000 people, that don’t have a municipal drinking water system.

Data provided by the Province of Ontario’s new open data site outlines drinking water sources for 204 municipalities in the province. That data, combined with population figures provided by Statistics Canada, show how many Canadians draw upon which water sources to survive.

The top five drinking water sources in the province are:

Lake Ontario: 6.3 million people

Ottawa River: 943,000 people

Groundwater spread across the province: 657,000 people

Lake Erie, Lake Huron: 366,000 people

Detroit River: 284,000 people

The bottom five drinking water sources in the province are:

Bay Lake: 387 people

Lost lake: 476 people

Killarney Channel: 505 people

St Joseph’s Channel: 566 people

Tukanee Lake: 607 people

HOW SAFE IS YOUR DRINKING WATER?

Each water source is tested several times a year. The latest testing data is only available for 2010-2011, but most municipalities in Ontario score surprisingly well. Each water system is assigned two scores: An overall percentage of tests that meet provincial standards, and a separate “inspection rating.”

The Inspection Rating is a weighted score based on the likelihood a failed test will result in serious consequences like public disease. A lower score means more serious infractions were measured. A higher score means cleaner water.

Check out our interactive map and see just how safe your water is among these 144 municipalities.

Click each dot to see the municipality name, population, water system and ratings.

WHERE DOES YOUR DRINKING WATER COME FROM?

Most Ontarians get their drinking water from surface water like lakes and rivers, but groundwater is also common. Check out our interactive map to find your municipality and see where your drinking water comes from. Water source data provided by the Province of Ontario. Population data provided by Statistics Canada.

Click each dot to see the municipality name, population and water system.

NO MUNICIPAL DRINKING WATER SYSTEM

Up to 140,000 Ontarians, mostly in small communities, are without a municipal drinking water system at all. While many of them are in the Northern reaches of the province, a solid portion are also in the well-populated southern areas.

According to a spokesperson for the Ministry of the Environment, “not everyone in Ontario get their drinking water from a municipal system.”

“We have several categories of other systems, but generally they would include private wells, private systems at facilities or businesses serving the public (i.e. a motel or restaurant on its own well), systems serving a residential development (ie a year-round mobile home park or subdivision that doesn’t have municipal servicing),” she said.

Here are the 42 municipalities that don’t have a municipally run water system licensed by the province.

Click each dot to see the municipality name, population and water system.